Tension device for sewing-machines.



C. B. ATWOOD.

TBNsmN DEVICE PoR SEWING MACHINES.

APPLIGATION IILBD JAN.31, 1912.

1,129,945.. Patented mmar.2,1915.

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C. B. ATWOOD.

TENSION DEVICE FOR SEWING MAGHNES.

APPLIGATION FILED JANA s1, 1912,

1,129,945, Patented Mar. 2, 1915.

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CLARENCE B. .ATWOOD, OF BELVIDERE, ILLINOIS, ASSIGNOR TO NATIONAL SEWING MACHINE COMPANY, OF BELVIDERE, ILLINOIS, A CORPORATION OF ILLINOIS.

razones.

Specification of Letters Patent.

Patented Mar. 2, 1915.

Application filed January 31, 1912. Serial No. 674,448.

To all whom it may concern .f

Be it known that I, CLAREN on B. A'rwoon, a citizen of the United States, residing at Belvidere, in the county of Boone and State of Illinois, have invented certain new and useful Improvements in Tension Devices for SewingMachines, of which the following is a specification.

My invention relates to sewing machines, and has more particular' reference to improvements in mechanism for tensioning the thread to properly form the stitches.

Primarily the Object of this invention is to provide improved means for insuring the necessary tension upon the thread as it passes from the supply spool to the needle, which tensioning means will be extremely simple and reliable in construction, neat in appearance, and uniformly effective in operation. y

A further object of my invention .is to provide improved thread tension mechanism which will automatically accommodate itself to the different sizes of thread used, and thereby maintain the proper sewing tension upon the thread throughout the range of sizes of thread which are used in sewing machines.

A further object of my invention is to provide improved tension mechanism which may ybe readily adjusted to operating conl ditions, and which, having been once set in that adjusted position, need not be dis# turbed during the operation of the machine.

further obj ect of my invention is to provide improved tension mechanism embodyf ing means for properlytensioning the thread during the operation of the machineand means for entirely relieving the thread of tension to permit the thread to be freely pulled when the cloth is removed from the machine.

A further object is to provide improved tension mechanism which will be practically fool-proof againstbeing threaded wrongly, and which will be fully protected against damage or disturbance.

In order to attain these ends and accomplish other objects hereinafter appearing, my invention'consists in the features of novelty in the construction, combination and arrangements of parts herein claimed, de-` scribed and shown in the accompanying` drawings which illustrate one embodiment of my invention, and in which- Figure l is a face view of a sewing machine head embodying my invention. Fig. 2 1s a similar view with the head plate or face plate removed to better show the inter'nal parts of the head. Fig.'3 is a side elevation of that portion of the head suiiicient to illustrate the application of my invention. Fig. 4: is a vertical sectional view of the irregular line 4 4: of Fig. 1. Fig. 5

is an enlarged central section of the main thread tension device. Fig. 6 is a face view of the main thread tension device. Fig. 7 is an enlarged central sectional view'of the auxiliary tension device on the line 7--7 of Fig. l. Fig. 8 is an enlarged detail on line 8-8`of Fig. 7. Fig. 9is a detail section on the line 9-9 of Fig. 7, and Fig. 10 is a perspective view of the tension release mechanism.

It'will be readily apparent, after having obtained an understanding of my invention, from the disclosures herein made, that my invention is applicable to various types of sewing machines, but for the purpose of an understanding of my invention, I have illustrated it as Vapplied to a sewing machineV head of well known construction.

Referring to the drawings, it will be seen that the sewing machine head l is of the hollow type, vwithin which the operating mechanism is contained. A needle bar 2 having a needle chuck 3 at its lower end, extends vertically through the head l. This bar is reciprocated vertically by the crank and connecting rods 4 and 5 respectively, driven by the shaft 6 shown in dotted lines in Fig. 2.

Parallel with the needle bar is a vertically movable presser foot bar 7, which carries at its lower end the usual presser foot 8 which, as is well known, coperates with other mechanism in the machine bed (not shown) to hold and feed the cloth in position while the stitches are being formed. This presser foot bar 7 has a long bore at its upper end which contains a spiral spring 9, the tension of which may be controlled and adjusted by means of a thumb screw l0 threaded into the upper portion of the head, the purpose of this arrangement, as is to exert a yielding pressure upon the cloth and feeding mechanism during the operation of the machine. Amanually 'operatedA finger lever ll-'is provided for raising and loweringythe presser bar. In the structure shown this lever projects into the interior of the head'through a slot in the side wall thereof, and is pivoted at 12 to the wall of the head. The portion of this lever adjacent its pivot is formed as a cam 13, which coperates with. the rearwardly turned lower end 14 of a multi-cam member 1G shown more clearly in Fig. 2. This multicam member 16y also has an. upper rearwardly turned end' 17 and bothof the ends are provided with, holes 17and 18 respectively through which the presser foot bar passes. The presser fcot bar has a. pin 1-9v which operates in an elongated slot 20 in the member 16, and in orde-r to provide a resilient lostv motion connection between the presser footbar and the member 16 a coiled spring is interposed between the pin 19 and the projection, 1-7. The purpose of this arrangement is to relieve the presser foot bar of allencumbrance, so that during the operation ,of the machine` the presser foot frame rests uponV the cloth. and vfeeding' mechanism under the sole action Y of the spring 9. The upper portion of the mem.- ber 16 is disposed substantially horizontally in front of the needle ba-r and haslong and short extensions 2,1 and 22 respectively. The long extension reaches to the upper portion of the head 1 and operatesin a guiding slot 23, as is clearly shown in Figs.,1 and et. The upper end 24 of this extension is beveled to form a cam. 22 is beveled at its upper end and. slightly curved; rearwardlyand also forms a cam.

In, sewing machines ofthis character it is customary to provide a removable face or head plate 25, it beingremovably clamped in position` by such means. asy al knurled head screw 2G.Y This is for the purpose of permitting access tothe interior of the head. tol facilitate cleaning and adjusting the parts, 'repairing and oiling. In this structure I have illustrated the tension mechanism as mounted upon a removable plate of vthis character, so that it may be removed therewith. The tension mechanism in this en bodiment of my invention is divided into two parts, namely: the main tension, device A and theauxiliary tensionl device B. The thread- C passes'f-rom the spool (not'shown) over, the top of the head and through the auxiliary tension device to the main tensionl device. From the main tension device it is threadedv through the auxiliary slack takeup D, main slack take-up E, a guide F and thence to the needle 21.

In the particular structure shown the auxiliary tension device B is positioned ad,- jacent the top of the head. At this point aV short hollow tube or boss 271 is screwed The short extension` into the face of the plate and is covered at its outer endl by a flat plate or head 27 (preferably circular), having a small central opening to admit the screw 28. This screw has a large (preferably circular and rounded) head or cap 29, which abuts against the smooth fiat face of the head 27. The thread C passes downwardly between the two members 27 and 29, and in order that the thread may be properly guided and maintained in place, I provide a narrow horizontal slot 30 in the member 27, as clearly shown in Fig. 9. The inner end of thisk slotis slightly enlarged, and thecontiguous metal is smoothed off so as not to cut the thread. In the operation of sewing machines the tension upon the thread and the facility with which this tension` may be controlled, play an important part inv the proper formation of the stitches. The fact is appreciated that the machine must accommodate a wide range in the size of thread, and since it would cause considerable annoyance and non-uniformitjy or results if the tension mechanism had to be adjusted for eve-ry size of thread, it is desirable that the tension mechanism automatically adapt itself to the various sizes ofv thread used. My improved tension mechanism is. designedi for this purpose. In the face of the head or plate member 27 I provide a shallow slot or machine cut 31, so as to leave a space between the adjacent faces of the head 29 and the face of the member 27. This machine cut intersects the guide slot 30 so that the thread may pass through the inner end. of the guide slot and directly downwardly through the machine cut 31. These parts` are preferably so proportioned that thread ranging in size down to about what is known as No. GO may freely pass through the cut. The coarser threads from about 60 down to what is known as No. 20,' require more tension. In order that the tension mechanism may automatically accommodate the several sizes of thread and` apply the proper tension, I provide means which will cause the head 29 to exert a yielding pressure so that the coarser threads, being more or less larger in diameter than the depth of the cut or groove 31, will pass downwardly through the cut and force the head 29 outward. The proper degree of pressure will be exerted in accordance with the size of the particular thread used. In this structure the pressure is obtained by means of a coiled spring 33 which is interposed between a collar on screw 28, and the head or member 27. The nut or collar 32 has a slot 34 in its face, by means of which it may be turned with a suitable tool to regulate the pressure of: the member 29 upon the thread. The end of the screw 28 ispreferably split (see Fig. 8) to-prevent the nut froml working loose, and thereby changing the adjustment.

It will be noted ythat the inner end of the screw 28 projects into the nut 23 in position to be actuated by the cam-end 24 of the extension 21 of member 16. Hence when Athe finger lever l1 is operated to raise the presser foot bar, the cam member 16 will also be raised. The cam 24 forces the screw 28 outwardly in counter-action to the spring 33, thus separating the members 27 and 29 and relieving the pressure of the member 29 upon the thread tension mechanism. The lowering or dropping of the presser foot again restores to action the tension mechanism without disturbing its adjustment.

The thread passes from the auxiliary tenv sion mechanism to the main tension mechanism A, as shown in Fig. 1, and I have constructed this mechanism so that it will ex-l ert a uniform tension upon all sizes of thread used. The thread isl preferably received on a rotary member such as a grooved pulley or wheel 40, around which the thread is given one turn. Outstanding from the face of the head plate 1 is a circular disk or member 41, having a depression 42 in its outer end or face.- The depression or recess is larger in diameter than the tension pulley 40,'and the pulley sets within this depression, as clearly shown in Fig. 5. The pulley is mounted upon a short centrally positioned stud 43, which projects through the disk member 41 and beyond the inner face of the plate 25. A forked leaf spring 44 is secured to the plate 25 and embraces the slotted inner end of the stud. This end of the stud 43 lies in thepath of cam extension 22 of the member 16, and is so arranged that when, as before described, the presser foot bar and the member 16 are raised, the cam extension 22 will co-act with the end of the .stud and .force it outwardly against the tension of the spring 44. The outer end of the stud 43 is threaded internally and externally. It has a large rounded cap or head 45. This cap also has a depression 46 in its inner face, into which the other edge of the pulley sets. Between the pulley wheel 40 and the adjacent inner face ofthe cap 45 and the disk 41 I interpose friction washers 47, so that when the pulley wheel is clamped between these friction washers by the action of the spring 44, a yielding resistance is offered to the turning of the wheel, and tension will accordingly bev applied to the thread. It will readily be seen that by turning the cap 45 upon the stud the degree of resistance offered to the wheel may be varied as desired. j The adjusting of this tension mechanism is preferably performed at the factory before the machine is shipped, and in order to preventthe user of the machine from disl turbing the adjustment, I split the end of the stud and provide a taper head screw 48 in the end of the stud. This expands the Vend of the stud and locks the cap 46 firmly as the presser foot bar is lowered the partsy are restored to normal position, but the ad.- justment is not in any way disturbed.

It will be noted that the tension mechanism is extremely simple, as the parts are so arranged, that it is practically impossible to thread the machine wrong. The outward surface of the main and auxiliary ten- .sion devices are perfectly smooth, and all sharp corners are avoided, hence these parts may be readily wiped and cleaned with a cloth without catching any of the ravelings and loose threads. Furthermore, the thread cannot enter the tension mechanism in any way except the right Way. The tension pulley 40 is protected by the cap 45 and the disk member 41, the rims or edges of these members overhanging the pulley in such manner that it is practically impossible for the thread to get in behind the pulley and Wind around the shaft. Furthermore, when the-presser foot bar is raised, this being done at times when the cloth is shifted or removed from the machine, the thread is entirely relieved of the tension effect of the main and auxiliary tension devices, and the thread may be freely pulled through without any resistance to it.- As soon as the presser foot bar again drops the same tension on the thread is again restored.

What I claim is:

1. In a thread tension mechanism for sewing machines, a main tension device and an auxiliary tension device comprising a stationary member having a depression in its face adapted to receive the thread, and a normally' inactive member covering said depression and adapted to be brought into operation to effect a yielding pressure upon thread larger than a certain size.

Y 2. In an automatic thread tension mechanism for sewing machines, a main tension device and an auxiliary tension device comprising two relatively separable members having a suiiicient opening therebetween for admitting threadsv of certain sizes, and means for causing one of said members to exert a yielding pressure when threads of certain other vsizes are passed through said opening.

3. In a thread tension mechanism for sewing machines, a main tension device and an auxiliary tension device comprising a stationary Hat faced member having a recess extending across its face, in combination with a normally inactive pressure membery disposed over said depression and a spring for said pressure member adapted to be brought into action to' cause pressi'irev upon threads of certain sizes when said threads are passed through said recess.

4. In a thread tension device for sewing machines, a main tension device and an aux- 'n guideslot communicating with said depression. for guiding the [th-read thereinto;

5. The improvements herein described comprising a sewing machine head, in com-` bination with a thread tensiony device- V mounted thereon and comprising a pair of tension clamps having ain openingorl thread slot therebetween'through whichI threads of certain sizes: may freely pass, said members being adapted to be'v rendered active to exert pressurelupon threads of a difieren-t certain sizes when passed through said slot and a second tension device adapted to exert ten-V sion'. on thread'sof all sizes.

6. An automatic thread tension device for sewing machines, comprising a fixed' member having' a thread slotl in its face, a nor-v mally inactivev member normally covering saidf slotspring mechanism for' causing said memberv to exert a yielding pressure upon threads of certain sizes when passed through said slot, means for regulating' the i pressure of said member and means for exerting tension on threads of all sizes usedI with said tension device.'A

7. In a thread check for sewing machines, thecombination with af fixed member and a -401 normally inactivevpressure member coperf than a certain size, aspringv arranged within said hollow member yieldingly holding said pressure member against said fixed member, whereby to` exert .pressure uponthreads coarser thanf said `certain size whenv passed. throughx said groove andi an addi tional tension` device? coiperating with threads? used.' with said? check.

9.` The improvements: herein'l described, comprising a sewing?l machine head', in"y combination` with: a: member.y secured". te andiy said device.

10. In a sewing machine, an operating head and a head plate secured thereto, in combination with a stud projecting from said plate, and having a flatinember at its end, a guide slot in said {iat member, a thread groove' in the face of said member intersecting said slot', a thread tensioning device coperating with and arranged to extend across said groove, and means for holding said tensioning device in yielding relation to a thread passing through said groove of larger diameter than the depth of thev groove.

11. The improvements herein described, comprising a sewing machine head plate, in combination with a hollow stud mounted upon saidv plate, a grooved plate positioned at the end of said stud and having a guide slot intersecting the groove in said plate, a stem projecting through said hollow stud andv having at its outer end a hat faced head abutting said grooved plate, a collar on said stem within said hollow stud, and a spring interposed between said collar and said grooved plate for causing said fiat faced head to exert a yielding pressure upon threads of larger size than the depth of the groove in said grooved plate.

12. The improvements herein' described, comprising a' sewing machine head plate, in combination with a flat metal disk mounted upon said plate and having a thread groove in its face and a guide slot cut in its edge, said guide slot intersecting said groove and adapted to directl the thread into said groove, a pressure disk normally covering said groove, a stem carried by said pressure disk and extending through said fiat disk, an adjustable collar on said stem, a coil spring surrounding said stem and constantly acting against said collar to hold said disks in contact and adapted to cause said pressure diskto exert a yielding pressure upon threads larger than the depth of said groove, and means whereby said collar may be turned' t'o regulate the degree of pressure upon the thread.

13. In al device of the character described, a main' tension member adapted to exert a substantially'constant tension, and an auxiliary tension member adapted to exert tension on threads of'cert'ain sizes and tepel-A mit threads of certain other sizes to freely pass said auxiliary tension member. Y

14. In a` device of the character described,

a main tension member adapted t'o exert tension on threads of all sizes used there- Witl1,' and an auxiliary tension member adapted to kexert tension on threads of oertain sizes and to permit threads of certain other sizes to freely pass said auxiliary tension member.

15. lin a device ofthe class described, a main tension memberv adapted to exert a substantially constant tensiomand an auX- iliary tension member adapted to exert pres-4 sure on threads coarser than certain sizes and to permit threads of finer sizes to freely pass said auxiliary tension member.

In testimony whereof I have signed my name to this specification, in the presence of 15 the subscribing Witnesses, on this 22nd day of kJanuary A. D. 1912.

CLARENCE B. ATWOOD. Witnesses:

J. E. WARREN, FRANK D. NEFF, FRANK L. GooDRIoH.

Copies of this patent may be obtained for ve cents each, by addressing the Commissioner of Patents,

Washington, D. C. 

